Therefore, the GGT isoform assay is highly valuable in clinical diagnostic and prognostic assessment and can be used to accurately determine the degree of liver disease types, such as distinguishing alcoholic liver disease from nonalcoholic fatty liver disease, and can also be used to monitor disease progression and therapeutic efficacy, such as in liver transplantation patients, as it can be used as an indicator to assess the recovery of grafted liver function and rejection reactions. Here, GGT1 is linked to metabolic dysfunction-associated steatotic liver disease.